Preheat your oven to 350°F (175°C) and line a 12-cup muffin tin with paper liners. This ensures your cupcakes don’t stick and makes cleanup much easier.
In a large bowl, whisk together the flour, sugar, cocoa powder, baking soda, and salt. Make sure there are no large clumps of cocoa, as these can leave bitter spots in the finished cake.
Add the warm water, vegetable oil, vanilla extract, and vinegar to the dry mixture. Whisk until the batter is smooth. The vinegar reacts with the baking soda to help the cupcakes rise and stay moist.
Divide the batter evenly among the 12 liners. Bake for 18 to 20 minutes, or until a toothpick inserted into the center comes out clean. Transfer the cupcakes to a wire rack and let them cool completely before frosting.
In a medium bowl, beat the softened butter until creamy. Gradually add the powdered sugar, heavy cream, and clear vanilla. Beat on high speed for 3 to 5 minutes until the frosting is very stiff and white. It needs to be firm to hold the ghost shape.
Fit a piping bag with a large round tip. Hold the bag vertically over the center of a cooled cupcake. Squeeze a large dollop, then pull up slightly, squeeze another smaller dollop on top, and pull up quickly to create a pointed “head.”
Carefully place two mini chocolate chips near the top of each frosting swirl to act as the ghost’s eyes. Press them in gently so they stay in place. Your spooky cupcakes are now ready!